High resolution monolithic RGB array

Abstract

A light emitting diode structure comprising a p-type region and an n-type region; and a light emitting region for recombination of charge carriers injectable by the p-type region and the n-type region, wherein at least one of the n-type region and the p-type region is formed at least partially in a via through the light emitting region, wherein the via defines a boundary of a light emitting surface of at least one pixel.

Description

TECHNICAL FIELD

[0001] The present invention relates to light emitting diode structures and methods of forming light emitting diode structures. In particular, but not exclusively, the present invention relates to high resolution monolithic arrays of light emitting diodes. BACKGROUND

[0002] Conventional light emitting pixels of red-green-blue (RGB) micro light emitting diode (μΙED) arrays are typically implemented using pick-and-place techniques, or by using color conversion materials deposited or integrated into standard planar light emitting diode (LED) structures. However, when the pixel pitch in such arrays is reduced to very small pitches (e.g., less than 5 μιη) in order to provide higher resolution arrays, many difficulties arise.

[0003] For example, the use of pick-and-place techniques can be impractical due to high cost, low throughput, and limitations in positional accuracy when transferring micro light emitting diodes. In the case of color conversion, the use of such techniques is limited by the size of the phosphor used for color conversion, which is typically greater than 10 μιη (i.e., greater than the pixel pitch in very small pitch arrays required for higher resolution). Furthermore, color conversion techniques can have poor reliability and low efficiency due to the small absorption coefficient associated with quantum dots (QDs). For example, a thickness of color conversion QD material of more than 10 microns is required to fully absorb the blue radiation output exciting them, thus making it unsuitable for very small pixel pitch arrays.

[0004] In order to avoid having to transfer LEDs, and in order to provide a high quality effective radiation output, it would be beneficial to provide a native array of LEDs on the same substrate. One method for constructing a native array of LEDs on the same substrate is selected area growth of nanowires, which is an array of individual structures grown substantially perpendicular to a patterned growth substrate to form a light emitting structure, where the light emitting surface is defined by the cross-sectional area of the nanowire, employing a typical epitaxial quantum well structure grown between epitaxial n-type and p-type doped layers. However, the growth of nanowires is typically difficult to control and can be severely limited in terms of light efficiency and color gamut due to poor light extraction efficiency and high levels of impurity incorporation. SUMMARY

[0005] To alleviate at least some of the above problems, there is provided a light emitting diode structure according to the appended claims. Furthermore, there is provided an array of light emitting diode structures and a method of forming one or more light emitting diode structures according to the appended claims.

[0006] In one example, there is provided a light emitting diode structure comprising: a p-type region, an n-type region, and a light emitting region for recombination of charge carriers injectable by the p-type region and the n-type region, wherein at least one of the n-type region and the p-type region is formed at least partially in a via through the light emitting region, wherein the via defines a boundary of a light emitting surface of at least one pixel. Advantageously, the material used for injecting charge carriers into the light emitting region is also used to define the boundary of the light emitting surface of the at least one pixel, whereby the pixels are isolated while still providing a source of charge carriers that can effectively recombine and emit light on the light emitting surface of the pixel.

[0007] Preferably, the light emitting region comprises at least one epitaxial quantum well layer. Advantageously, the epitaxial quantum well layer is grown with high crystalline quality, resulting in efficient light generation.

[0008] Preferably, the via is capable of injecting lateral charge carriers in the light emitting region. Advantageously, injection of lateral charge carriers in one or more quantum wells in the light emitting region enables more efficient hole injection into the light emitting region.

[0009] Preferably, both the n-type region and the p-type region are formed at least partially in a via through the light emitting region. Advantageously, such an arrangement enables lateral injection of charge carriers from both the n-type region and the p-type region, resulting in efficient recombination. Advantageously, the same regions used for lateral charge carrier injection are also used to isolate the pixels.

[0010] Preferably, the light emitting diode structure comprises a further via, wherein the via and the further via are arranged to provide an anode and a cathode. Advantageously, such an arrangement enables lateral injection of charge carriers from both the n-type region and the p-type region, resulting in efficient recombination. Advantageously, the same regions used for lateral charge carrier injection are also used to isolate the pixels. Additionally, the anode and the cathode can be selectively energized to control the light emitted from the light emitting diode structure.

[0011] Preferably, the light emitting diode structure comprises a further light emitting region. Advantageously, the light emitting regions can be excited simultaneously or individually, and can be configured to have the same or different dominant peak wavelengths.

[0012] Preferably, the light emitting region and the further light emitting region are separated by an undoped region, thereby providing a stacked light emitting region. Advantageously, carrier injection into different light emitting regions is achieved by forming a via connection to the light emitting region without the need for a layered n-GaN and p-GaN stack as seen in conventional LED structures. Advantageously, in the absence of a p-type doped layer, there is no problem of p-type dopant diffusion and the multiple quantum wells (MQW) of the light emitting region can be brought closer together without the need for a tunnel junction. Furthermore, no electron blocking layer is required in this structure.

[0013] Preferably, the via passes through both the light emitting region and the further light emitting region. Advantageously, a common connection is provided for the light emitting regions, thereby making the processing of the initial epitaxial structure simpler.

[0014] Preferably, the light emitting region and the further light emitting region are configured to radiate light of different wavelengths. Advantageously, the structure can radiate light of different dominant peak wavelengths, thereby the structure can be implemented within a multi-colour array.

[0015] Preferably, the light emitting region and the further light emitting region are arranged such that the surface area of the light emitting region and the further light emitting region partially overlap. Advantageously, in plan view, the different regions are arranged to provide a light emitting surface based on different light emitting regions (and therefore can be configured to provide different light emission, for example different intensities, times, or colours, etc.).

[0016] Preferably, the light emitting diode structure comprises at least three light emitting regions, wherein one light emitting region radiates blue light, one light emitting region radiates green light, and one light emitting region radiates red light. Advantageously, the use of three light emitting regions provides more flexibility, including the ability to provide red green blue (RGB) light for a colour display at high resolution.

[0017] Preferably, the via is a grid via defining an array comprising a plurality of pixels, preferably wherein the grid is arranged to provide a common electrode. Advantageously, the connection can be achieved in one processing step. Furthermore, the definition of the pixels by the use of a grid via means that there is no need for etching of electrical isolation between the pixels, thereby allowing tighter pixel integration.

[0018] Preferably, at least two of the pixels are configured to radiate light of different wavelengths. Advantageously, multiple colour outputs can be provided from a single array.

[0019] Preferably, the further via comprises a pillar via and an n-type or p-type region is formed in the further via. Advantageously, the pillar via provides an efficient way of providing carrier injection.

[0020] Preferably, the columnar via is arranged to provide an electrode, thereby enabling control of the radiation in the pixel defined by the via. Advantageously, the electrode can be used to selectively control the radiation from a single pixel in a high resolution array of pixels.

[0021] Preferably, the light emitting region and / or the further light emitting region is formed on an undoped epitaxial layer. Advantageously, the undoped epitaxial layer gives electrical isolation of the pixel.

[0022] Preferably, the light emitting region and / or the further light emitting region is formed between undoped epitaxial layers. Advantageously, the undoped epitaxial layers give electrical isolation of the pixel and enable processing of the epitaxial structure for single pixel connection by etching through the light emitting region and / or the further light emitting region formed between the undoped epitaxial layers.

[0023] Preferably, the undoped epitaxial layer is formed on a barrier layer configured to block longitudinal carrier diffusion. Advantageously, the light emitting structure can be formed on a doped material that can form part of the substrate and / or preferred growth techniques, whilst enabling isolation of the light emitting region, thereby forming one of the n-type and p-type regions to pass through the light emitting region.

[0024] Preferably, the light emitting diode structure is a gallium nitride based structure. Gallium nitride is known for its performance in providing efficient light emitting diode devices with a range of dominant peak wavelengths. Growth of gallium nitride structures is well developed and growth and processing of this material is controllable to provide high quality devices. Therefore, preferably, the undoped epitaxial layer is gallium nitride.

[0025] Preferably, the barrier layer is AlGaN. Advantageously, the barrier layer provides a stable surface for subsequent processing steps.

[0026] Preferably, at least one of the n-type and p-type regions is formed in a via connected to the n-type region or the p-type region of the plane respectively. Advantageously, the use of a planar region provides for light emission due to carrier diffusion and can advantageously reduce etch damage and loss of active area that would otherwise be used for a central via etch to laterally inject carriers into the light emitting region.

[0027] Preferably, the n-type region is formed in the via by selective area growth of n-type material. Advantageously, the growth of the selected area at least partially heals etch damage. Furthermore, passivation is unnecessary as there is no remaining open surface cutting through the multiple quantum wells.

[0028] Preferably, the p-type region is formed in the via by selective area growth of p-type material. Advantageously, the growth of the selected area at least partially heals etch damage. Furthermore, passivation is unnecessary as there is no remaining open surface cutting through the multiple quantum wells.

[0029] Preferably, the via is an etched via. Techniques of anisotropic etching are known and enable the growth and subsequent processing of larger scale epitaxial structures in order to provide a light emitting diode structure with pixel boundaries defined by the etched vias. This means that, in contrast to smaller scale techniques such as patterned nanowire growth, known techniques for growing high quality and efficient epitaxial structures can be used.

[0030] Preferably, the light emitting surface has an area based on the diffusion length of the carriers within the light emitting region. Advantageously, the shape and / or size of the light emitting surface is optimisable based on the length of the diffusing carriers, which is useful in providing uniform light emission in micro-LEDs.

[0031] Preferably, the light emitting surface area is less than or equal to 100 pm 2 , and preferably less than or equal to 16 pm 2 . Advantageously, the use of vias comprising n-type or p-type material to define the pixels enables the formation of micro-LEDs with light emitting surfaces which provide high resolution for the pixels.

[0032] Advantageously, the use of vias comprising n-type or p-type material to define the pixels enables the formation of micro-LEDs with light emitting surfaces which provide high resolution for the pixels and can form an array. Such an array is suitable for connection to a backplane and thus integration into a high resolution display or other high resolution array which can be monochromatic or polychromatic.

[0033] Preferably, the light emitting diode structure and / or micro-LED array is provided by forming a plurality of epitaxial layers on a substrate. Advantageously, forming a plurality of epitaxial layers on a substrate means that a structure providing high quality can be grown continuously, reducing growth time and impurities in growth.

[0034] Preferably, the plurality of epitaxial layers comprises an n-type region and a light emitting region. Advantageously, such a plurality of epitaxial layers comprises layers of a conventional LED structure. Advantageously, a conventional LED structure (which can terminate before a p-cladding) can be used as a basis for subsequent processing of a monolithic micro-LED array.

[0035] Preferably, the plurality of epitaxial layers is etched such that the etching is through the light emitting region to provide a via defining a pixel boundary. Techniques of anisotropic etching are known and enable the growth and subsequent processing of larger scale epitaxial structures in order to provide a light emitting diode structure with pixel perimeters defined by the etched vias. This means that, in contrast to smaller scale techniques such as patterned nanowire growth, known techniques for growing high quality and efficient epitaxial structures can be used.

[0036] Preferably, a p-type region or an n-type region is grown in the etched via.

[0037] Preferably, a further via is etched for the p-type region or the n-type region.

[0038] Preferably, the further via is through a light emitting region configured to provide a particular wavelength.

[0039] Preferably, a further via is etched for the p-type region or the n-type region, wherein the further via and the further via are arranged to allow carrier injection into different light emitting regions, thereby providing light of different wavelengths.

[0040] Preferably, etching a further via for the p-type region or the n-type region comprises etching at least partially through at least one light emitting region, so as to locally remove an unwanted longest wavelength.

[0041] Other aspects of the application will become apparent by consideration of the description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0042] A detailed description of embodiments of the application will be made with reference to the accompanying drawings, in which:

[0043] Figure 1A A cross-sectional view of an epitaxial structure is shown;

[0044] Figure 1B A cross-sectional view of a processed epitaxial structure is shown;

[0045] Figure 1C A cross-sectional view of a processed epitaxial structure is shown;

[0046] Figure 2A A cross-sectional view of a processed epitaxial structure is shown;

[0047] Figure 2B A plan view of a processed epitaxial structure comprising Figure 2A is shown;

[0048] Figure 3A A cross-sectional view of a light emitting structure is shown;

[0049] Figure 3B A plan view of a light emitting structure comprising Figure 3A is shown;

[0050] Figure 4 A cross-sectional view of a processed light emitting structure is shown;

[0051] Figure 5 A cross-sectional view of a light emitting structure is shown;

[0052] Figure 6 A cross-sectional view of a processed light emitting structure is shown;

[0053] Figure 7 A cross-sectional view of a light emitting structure is shown;

[0054] Figure 8 A cross-sectional view of a light emitting structure is shown;

[0055] Figure 9 A cross-sectional view of an epitaxial structure with three different light emitting regions is shown;

[0056] Figure 10A A cross-sectional view of a processed epitaxial structure is shown including Figure 9 ;

[0057] Figure 10B A plan view of a processed epitaxial structure is shown including Figure 10A ;

[0058] Figure 11A A cross-sectional view of a further processed epitaxial structure is shown including Figure 10A ;

[0059] Figure 11B A plan view of a further processed epitaxial structure is shown including Figure 11A ;

[0060] Figure 12A A light emitting structure with three different light emitting regions is shown;

[0061] Figure 12B A plan view of a light emitting structure is shown including Figure 12A ;

[0062] Figure 13A A processed light emitting structure is shown including Figure 12A ;

[0063] Figure 13B Lateral carrier injection in the structure of Figure 13A ; and

[0064] Figure 14 An implementation of a pixel is shown having three different light emitting regions within the pixel, the pixel defined by a boundary formed by a via through the light emitting regions. DETAILED DESCRIPTION

[0065] Light emitting diodes (LEDs) are typically formed by processing a light emitting structure grown in a reactor, for example a MOCVD (metal organic chemical vapour deposition) reactor, MBE (molecular beam) reactor or other chemical vapour deposition reactor, by forming epitaxial crystal layers on a relatively large wafer substrate. For the above reasons, known methods for creating arrays of high resolution micro-LEDs face difficulties in processing the LEDs resulting from crystal growth on a relatively large chip substrate to provide micro-LEDs for high resolution arrays. Nanowire LED arrays are used to overcome these processing issues resulting in difficulties in control of the growth process compared to conventional relatively large chip substrate LED growth and generally poorer performance.

[0066] The present disclosure describes micro-LEDs formed as part of a monolithic high resolution array by advantageously processing light emitting structures that can be grown on a relatively large chip substrate. Advantageously, smaller, more efficient and more degradation resistant primary colour pixels can be formed compared to colour converted pixels. Processing of epitaxial structures grown directly on a wafer means that there is no need to transfer millions of pixels (and associated faults in the transfer process) compared to pick and place assembly, so production throughput can be improved by forming the array of pixels on a wafer. Processing of standard planar epitaxial deposition layer growth means that multiple quantum wells (MQWs) are formed in a way that provides high quality growth and so have higher internal quantum efficiency (IQE) compared to nanowires. Furthermore, processing of epitaxial structures provides planar devices that are better suited to light extraction using standard surface patterning techniques.

[0067] In the following description, other advantages will be apparent from the description of the methods and structures. The methods are described below with reference to various processing steps (the processing steps can include steps performed in a growth reactor and outside of the growth reactor using other processing and / or growth equipment) that provide micro-LED arrays. The methods and structures are described with reference to III-V semiconductor materials. In particular, the methods and structures are described with reference to nitride structures including gallium nitride (GaN) based light emitting structures, which are well known to provide relatively efficient light emitting structures. However, in further examples, the methods and structures are applicable to light emitting structures based on other materials, in particular other semiconductor materials.

[0068] In the following drawings, like reference numerals are used to illustrate aspects of structures that are related to the same features or equivalent features provided by the same or similar processes.

[0069] Figure 1AA structure 100 is shown, which is an epitaxial structure 100 that forms the basis of a monochromatic micro-LED pixel array. Such a monochromatic micro-LED pixel array has a plurality of individual pixels, where each pixel can be individually addressable based on the way such a monochromatic micro-LED pixel array is connected to a power supply (e.g. depending on the arrangement of the backplane relative to the micro-LED pixel array).

[0070] The structure 100 is a GaN-based epitaxial multi-quantum well (MQW) structure grown by metal organic chemical vapour deposition (MOCVD), which is in effect an LED structure grown and terminated prior to a p-cladding layer which would otherwise provide a conventional pn-junction sandwiching a light emitting region formed to include at least one or more quantum wells. Advantageously, known techniques can be used to provide high quality material that can be processed to provide a monolithic high resolution micro-LED array.

[0071] In Figure 1A The n-doped (n-GaN) n-type region 102 is shown, on which is grown an AlGaN barrier layer 104 with 10% aluminum. The n-type region 102 is typically formed on a substrate (not shown). The AlGaN barrier layer 104 prevents diffusion of longitudinal carriers from the n-type region 102.

[0072] On the barrier layer 104 is grown an undoped region 106 (intentionally un-doped GaN), on which is grown a GaN-based superlattice structure 108. On top of the superlattice structure 108 is a light emitting region 110 with multiple quantum wells (MQW). The cross-section of the n-type region 102, barrier layer 104, undoped region 106, superlattice 108, and light emitting region 110 are shown as epitaxial layers grown on a substrate (substrate not shown, further the substrate is not the n-type region 102 itself).

[0073] On the barrier layer 104 is grown an undoped region 106 (intentionally un-doped GaN), on which is grown a GaN-based superlattice structure 108. On top of the superlattice structure 108 is a light emitting region 110 with multiple quantum wells (MQW). The cross-section of the n-type region 102, barrier layer 104, undoped region 106, superlattice 108, and light emitting region 110 are shown as epitaxial layers grown on a substrate (substrate not shown, further the substrate is not the n-type region 102 itself).

[0074] The light emitting region 110 has MQWs. Additionally or alternatively, the light emitting region 110 can have single quantum wells (SQWs). Additionally or alternatively, the light emitting region 110 can include one or more quantum dots or other structures to enable carrier recombination and light emission. Quantum wells and quantum dots confine carriers and, in use, provide a source of light based on radiative carrier recombination in the quantum structures after carrier injection through n-type and p-type regions when connected to a cathode and an anode, respectively.

[0075] Another barrier layer 112 is shown on top of the light emitting region 110, which is an AlGaN barrier layer 112. The barrier layer 112 provides a stable surface for subsequent processing steps.

[0076] Although the barrier layer 112 is shown as an AlGaN barrier layer 112, additionally or alternatively, the barrier layer 112 is formed of a different material, or can be excluded.

[0077] Although the light emitting region 110 includes MQWs, in further examples, the light emitting region 110 can have single quantum wells (SQWs). The light emitting region 110 includes multiple layers of material to form an active region. For example, the light emitting region 110 includes layers such as short period superlattices and / or undoped recovery layers to provide high quality crystalline material and radiation from the light emitting region 110. Additionally or alternatively, the light emitting region 110 can include one or more quantum dots. Quantum wells and quantum dots confine carriers and, in use, provide a source of light based on carrier recombination in the quantum structures after carrier injection through n-type and p-type regions when connected to a cathode and an anode, respectively.

[0078] Although the n-type region is typically formed on a substrate, alternatively, the n-type region itself can be a free standing substrate suitable for subsequent growth of crystalline layers. In one example, the substrate is a sapphire substrate. In other examples, the substrate is a silicon substrate or a GaN substrate.

[0079] The epitaxial structure 100 can be grown using a MOCVD reactor. Advantageously, such a structure 100 can be optimized for MOCVD growth and provide high quality growth to efficiently produce light. Additionally or alternatively, other deposition and / or growth methods can be used to provide the epitaxial structure 100, such as MBE.

[0080] The n-type region 102 is formed of n-type gallium nitride. However, in further examples, the n-type region 102 can be formed of and / or based on other materials. The barrier layer 104 is formed of aluminum gallium nitride, for example 10% aluminum AlGaN. However, in further examples, additionally or alternatively, the barrier layer 104 can not be used, or the barrier layer 104 can be formed of a different material. The superlattice 108 is formed of gallium nitride based materials. Additionally or alternatively, the superlattice 108 is formed of other materials. The light emitting region 110 includes at least one quantum well. Additionally or alternatively, the light emitting region 110 includes further quantum wells. Additionally or alternatively, the light emitting region 110 includes quantum dots or other quantum structures. The light emitting region 110 is a gallium nitride based region, where at least the quantum well is formed of a gallium nitride based material such as indium gallium nitride (InGaN) or aluminum indium gallium nitride (AlInGaN). Additionally or alternatively, different materials are used depending on the structure to be grown. The composition of the quantum well in the light emitting region 110 is determined based on the dominant peak wavelength selected for radiation from the light emitting region 110. The barrier layer 112 is formed of aluminum gallium nitride. Additionally or alternatively, different materials can be used to form the barrier layer 112. The light emitting region 110 does not contain any doping, for example, it does not contain silicon doping or magnesium doping that intentionally dopes the light emitting region 110 during growth. In further examples, doping is used in the light emitting region 110, which does not affect carrier injection so as to emit light via the light emitting surface of the pixel defined by the via through the light emitting region 110. In further examples, different semiconductor layers are grown or otherwise formed to provide the necessary infrastructure for handling the monolithic array of micro-LEDs.

[0081] Although a particular epitaxial structure 100 is shown in Figure 1A

[0082] Once the epitaxial structure 100 is provided, it can be processed to provide conductive regions through which carriers can be injected into the final structure.

[0083] Accordingly, Figure 1B A processed epitaxial structure 100' is shown. Figure 1A ​An epitaxial structure 100 is shown with an additional mask layer 114. The mask layer 114 is formed and processed using known techniques including photolithography techniques to selectively form holes and expose underlying portions of the epitaxial structure 100, e.g., the barrier layer 112. Once portions of the mask layer 114 are selectively removed, the underlying epitaxial structure 100 is selectively etched. This selective etching provides vias in the epitaxial structure 100. A via is formed by removing material so as to leave a path through the remaining material. Depending on the shape of the area exposed in the mask layer 114 and the depth of the etch, the via formed will have a corresponding form, in examples, it is in the form of a trench via or a columnar via. Although the via is formed by etching material to leave a trench, hole, or other path, in other examples, the via is additionally or alternatively formed by forming material so that, as opposed to removal of material, there is no material to form the via structure inside the other structure.

[0084] In examples, the mask layer 114 is silicon nitride. Additionally or alternatively, a different material can be used, e.g., silicon dioxide. Advantageously, silicon nitride is an effective and controllable mask layer 114 for subsequent processing steps.

[0085] Figure 1C An epitaxial structure 100” is shown that has been further processed with vias 115 that have been etched through the epitaxial structure 100. The vias 115 shown have been etched through the epitaxial structure 100 to the n-type region 102. To enable the vias 115 to be etched, photolithography techniques are used to pattern the mask layer and open holes in the mask layer to enable the material exposed by the holes formed in the mask to be etched. The vias 115 are shown in cross-section. In plan view, the vias 115 are formed in a grid structure (see, e.g., the grid of FIG. 2) to define pixels, with the vias defining the boundaries of the light emitting surface of each individual pixel 208 by passing through the light emitting region 110 to form trench vias 115 to isolate each individual pixel. The width 210 of the pixels 208 is the distance between the vias 115 shown. Figure 2B Figure 1C Once the vias 115 are formed in the epitaxial structure 100, selective overgrowth of the n-type material is formed. For example, this overgrowth or deposition of material can be performed in the vias 115 with the mask layer 114 remaining in place so that no growth occurs on the barrier layer 112. Accordingly,

[0086] A cross-sectional view of the processed epitaxial structure provided in FIG. 1 is shown. Figure 2A

[0087] ​​In one example, a dry etching technique such as a plasma based technique is used to form the via 115. Preferably, a wet etching process is used to recover any damage caused by the etching of the via 115. Additionally or alternatively, any suitable etching technique is used to form the via 115.

[0088] Figure 2A The same basic structure 100, 100', 100" as shown in Figure 1A , IB and 1C is shown, however, Figure 2A The structure 200 of Figure 2A The processed epitaxial structure 200 shows a deposition mask layer 114, which in one example is a silicon nitride layer, that has been etched to provide a via 115, as shown in Figures 1A to 1C The via 115 is etched vertically through the epitaxial structure 100 to the doped n-type region 102. Subsequently, an n-type overgrowth 116 of n-type doped GaN (n-GaN) is formed in the via 115 to provide a conductive region through the light emitting region 110.

[0089] Although a single pixel cross-section (with a width 210) is shown in Figure 2A , it will be appreciated that the selective etching of the epitaxial structure 100 provided by the selective etching and overgrowth of n-type material in the via trench will result in a grid of n-type that is an effective common electrode (in this case the cathode) for all of the pixels defined by the n-type overgrowth 116 through the light emitting region 110 of the epitaxial structure 100. Advantageously, the n-type material growth of the selective region is performed using a relatively high temperature metal organic chemical vapour deposition (MOCVD) reactor. This relatively high temperature anneal causes passivation and healing of any open MQW surfaces. There are no dangling bonds at the MQW periphery after processing and so passivation is no longer required. Thus, advantageously, a greatly reduced non-radiative recombination is achieved in the light emitting region 110.

[0090] The n-type overgrowth 116 is shown protruding from the surface of the masking layer 114. Advantageously, this enables the doped overgrowth to form a contact. The structure 200 is not shown to scale, but in an example, the thickness 202 of the structure formed on the n-type region 102 can be approximately 300 nm, with the n-type overgrowth 116 extending a further 700 nm in height 204 compared to the thickness 202 of the epitaxial structure 200. In one example, the width 206 of the via 115 can be approximately 800 nm. In further examples, the dimensions of the structure are determined by, for example, the technology used and the structure required. For example, the crystal habit of the material used can determine the growth shape of the material protruding above any masking layer surface. By etching through the hole already exposed in the masking layer 114, a grid can be formed by growing n-type material in the via 115, as Figure 2B is shown.

[0091] Figure 2B An example of a plan view 200' of the structure 200 is shown. The plan view 200' shows a larger number of pixels 208 than Figure 2A is shown. The skilled person will appreciate that the number of pixels 208 that can be formed by the methods described herein is not limited to Figure 2A the number of pixels 208 shown, and Figure 2B Figure 2B An example of a plan view 200' of the via 115 etched through the epitaxial structure is shown. The structure has n-type overgrowth 116 in the via 115. The grid structure is used to form a common electrode, for example a common cathode, using the n-type overgrowth 116. The grid can be used to define pixels 208 (only one pixel 208 is labelled, but it will be apparent that the matrix of n-type region overgrowth formed by the trench vias 115 is used to define a plurality of pixels 208), with the light emitting surface of each pixel 208 shown in the plan view 200' of the square pixels 208 as the area defined by the selectively etched vias 115 formed in the grid matrix with n-type overgrowth 116 in the vias 115. Although the via is formed by etching material to leave a trench, hole or other pathway, in other examples, additionally or alternatively, the via is formed by forming material, such that, in contrast to the removal of material, there is no material to form the via structure inside the other structure.

[0092] ​In an example, the width 210 of the pixel 208 is approximately 3 pm. Preferably, the width 210 of the pixel 208 is selected based on a carrier diffusion length for enabling efficient emission of light from the light emitting surface of the pixel 208. Advantageously, since the electrode formed by the n-type overgrowth 116 extends around the boundary of each pixel 208 and through the light emitting region 110, no further electrical isolation of the pixels 208 is required. In other examples, the light emitting surface of each pixel 208 is less than 100 square microns. In further examples, the light emitting surface of each pixel 208 is less than 16 square microns. Although the pixels 208 are shown as having the same size and shaped light emitting surface, in further examples, the array is provided with different pixels having different shapes and / or sizes.

[0093] Once the effective cathode provided by the n-type overgrowth 116 in the via 115 is provided, the anode is provided based on a p-type overgrowth 118 formed in another via 117.

[0094] Figure 3A The structure 200 is shown Figure 2A The structure 200 has been further processed so as to provide a light emitting structure 300. The n-type overgrowth 116 is shown in a via 115 through the light emitting region 110 to the n-type region 102. Also shown is a via 117 through the light emitting region 110, whereby a p-type overgrowth 118 is formed in the other via 117. This is achieved by depositing a further mask layer (shown as mask layer 120 on the n-type overgrowth 116 and added to the mask layer 114) on the mask layer 114 and selectively patterning the further mask layer 120 and the mask layer 114 to create openings to expose the underlying structure and etching down through the mask layers 114, 120 using known lithography and etching techniques until the active region provided by the light emitting region 110. As described for the manufacture of the via 115 for the n-type overgrowth 116, the via 117 for the p-type overgrowth 118 is formed using a dry etching technique. In one example, a wet etching treatment is used to restore damage caused by the dry etching if necessary. Figure 2A

[0095] The other via 117 is a columnar via formed centrally within the pixel boundary defined by the via 115 through the light emitting region 110. Additionally or alternatively, the other via 117 is located in any suitable position so as to provide light emission. The cross-sectional shape of the other via 117 when viewed in plan is determined by the patterning and etching steps used to provide the other via 117. The via 117 has a width of approximately 800 nm. In other examples, the width dimension of the via 117 is set to meet preferred implementations with respect to carrier injection and pixel arrangement.

[0096] As shown by the arrows, in​Figure 3A From the n-type overgrowth 116 and the p-type overgrowth 118 to the light emitting region 110, the n-type overgrowth 116 provides an effective cathode, while the p-type overgrowth 118 provides an effective anode, allowing for lateral injection of carriers into the light emitting region 110 when a suitable power source is used. This lateral carrier injection in the light emitting region 110 provides for more efficient carrier injection, including more efficient hole injection, thus providing for more efficient light emission. The carriers injected into the light emitting region 110 can be based on a carrier diffusion length of the carriers injected into the multi-quantum well structure of the light emitting region 110 to provide for light emitted from the light emitting surface defined by the pixel boundaries formed by the n-type overgrowth 116 etched through the light emitting region 110, located within the via 115. A plan view 300’ of the light emitting structure 300 is shown in Figure 3B

[0097] Figure 3B shows the n-type overgrowth 116 formed in the grid vias 115 etched through the structure 100 as described with respect to Figure 1A In addition, it shows the p-type overgrowth 118 formed in the central via 117 of the pixel 208 defined by the n-type overgrowth 116 in the via 115 of the common electrode provided by the n-type overgrowth 116. In an example, the central via 117 is formed in each pixel 208 to be addressed. The p-type overgrowth 118 is shown in the central via 117 in each pixel 208. This arrangement of a common n-type region that can form a shared cathode electrode and a single columnar p-type overgrowth region that can form an independently addressable anode electrode can be used to excite a single pixel 208 in a single color high resolution micro-LED array.

[0098] Advantageously, the n-type and p-type regions can be overgrown compared to known selective area growth techniques. This eliminates the problems of poor uniformity and composition pulling typically encountered when growing AlGaN and InGaN alloys on patterned surfaces.

[0099] While the etching based on the epitaxial structure shows the via 115 forming a trench through the light emitting region 110 of the epitaxial structure defining the light emitting surface of the pixel 208, in further examples, other techniques can be used to form a light emitting region with a via through the light emitting region to define the boundaries of the light emitting surface of a pixel in a pixel array.

[0100] Figure 4 A cross-sectional view of the processed light emitting structure described with respect to FIGS. 1-3 is labeled. The processed light emitting structure is flipped over Figure 3A ​to provide a processed light emitting structure 400 to extract light through the n-type region 102, thereby avoiding absorption due to the p-type contact 404 Figure 4 The arrows in the figure show the direction of light from the light emitting surface of the pixel 208 defined by the via 115 through the light emitting region 110.

[0101] Furthermore, Figure 4 An insulating layer 402 is shown. The insulating layer 402 insulates the n-type overgrowth 116 from any connection points used to contact the p-type overgrowth. Preferably, the insulating layer is silicon dioxide. The anode of each pixel 208 to be addressed is connected to the shown contact 404. In addition, a mirror / blocking layer 405 is shown which is configured to reflect light radiating from the light emitting region 110 away from the light emitting surface defined by the n-type overgrowth 116 in the via 115 defining the boundary of the pixel 208. Advantageously, the contact 404 can be connected to a backplane such that the contact 404 of each pixel in the array is contacted and independently addressable.

[0102] A metal mesh 408 is shown in the figure which is designed to contact the common n-type mesh of the light emitting array. Such a metal 408 mesh is aligned with the n-type overgrowth 116 in the via 115 in order to maximise light extraction, and thus can take substantially the same form as the mesh provided by the via 115 etched through the light emitting region 110 of the epitaxial structure 100 when viewed from plan.

[0103] A transparent conductive layer 406 is also shown in the figure which can preferably be indium tin oxide (ITO) formed around and / or between the conductive metal mesh 408 in order to provide conductive and efficient light extraction from the pixels 208 of the light emitting array of micro-LEDs.

[0104] Although cross-sections of individual pixels are labelled in Figures 1 to Figure 4 Whilst cross-sections of individual pixels are labelled in Figures 1 to Figure 2B and 3B In further examples, different shaped pixels can be provided, for example by etching a different pattern through the epitaxial structure shown in Figure 1.

[0105] Whilst the concept of providing a template defining a pixel through the light emitting region and using a central etched via 117 through the light emitting region and n-GaN n-type region 102 with a p-type overgrowth 118 provided by p-GaN is shown, different implementations of the concept are possible in further examples, some of which are described with respect to the following figures.

[0106] For example, different structures can be used to provide a monolithic high resolution micro-LED array with through-holes defining pixels, using either lateral carrier injection or carrier diffusion into the quantum structure.

[0107] Figure 5 A cross-section of a light emitting structure 500 according to the above concepts is illustrated (where one pixel of the array of pixels is defined, the same nomenclature is used for drawing parallel lines between the pixels 208, for example Figure 2B the pixel width 210 described in relation to figure 1). The same epitaxial structure 100 is illustrated in the figure as described in relation to figure 1. However, instead of etching through the mask layer 114 to form through-holes 115 connected to the n-type region 102, through-holes 115 are illustrated etched through the light emitting region 110, which terminate in the undoped region 106, so as to provide trenches for the p-type overgrowth 118. The p-type overgrowth 118 in these trench through-holes 115 is used to provide a common anode grid through the light emitting region 110, which defines the pixels 208. In a method complementary to the method described in relation to figures 1 to Figure 4 In a complementary method to the method described in relation to figures 1 to 4, a cathode can be provided in each pixel 208 by etching through the central through-hole 117 and depositing / growing n-type overgrowth 116 material in the through-hole 117. The patterning and etching steps are implemented depending on the particular structure to be produced, and known techniques can be used.

[0108] Figure 6 A processed light emitting structure 600 is illustrated based on Figure 5 the light emitting structure 500 described in relation to figures 1 to 5. The processed light emitting structure 600 is an inverted structure relative to Figure 5 the structure described in relation to figures 1 to 5, where the intention is to extract light through the light emitting surface defined by the p-type through-hole grid, but to be extracted through the n-type region 102 (the arrows represent the direction of light out of the structure, which in three dimensions can be understood as illuminating the pixels 208 in such a way that the boundaries of the light emitting surface of the pixels 208 are defined by the through-holes 115 through the light emitting region 110). A common anode grid 602 is provided to be in contact with the p-type overgrowth 118 in the through-holes 115 etched through the light emitting region 110. Contact points 604 are formed to enable carrier injection into the n-type overgrowth 116 of the cathode for each light emitting pixel to be addressed. The contact points 604 can be reflective so as to enhance light extraction from the light emitting structure 600. The structure can be planarised so that the planarised insulator layer 402 provides a surface onto which a backplane can be connected to connect with the contact points 604 in other pixels 208 and other contact points 604, so that each pixel 208 can be addressed individually.

[0109] Figure 7 and Figure 8 A cross-section of a light emitting structure 500 according to the above concepts is illustrated (where one pixel of the array of pixels is defined, the same nomenclature is used for drawing parallel lines between the pixels 208, for example Figure 4The light emitting structure is described, but without the other via 117 through the light emitting region 110. The figure shows an undoped region 702 that separates the light emitting region 110 from the central overgrowth 116, 118 of the patterned and doped region. Figure 7 A light emitting structure 700 is shown that has a p-type overgrowth 118 in the via 115 defining the pixel 208, and has a central n-type overgrowth 116. Figure 8 A light emitting structure 800 is shown that has an n-type overgrowth 116 in the via 115 defining the pixel 208, and has a p-type overgrowth 118. For Figure 7 and Figure 8 For the structure of

[0110] Although a monochromatic high-resolution micro-LED array has been described above, a multi-color high-resolution micro-LED array can be provided based on etching through multiple light emitting regions, as described herein.

[0111] Figure 9An epitaxial structure 900 is shown. The epitaxial structure 900 is provided in a similar manner to the epitaxial structure 100 described with reference to Figure 1. However, the structure 900 has three light emitting regions, rather than having one light emitting region 110 arranged to radiate light having a peak dominant wavelength. Shown in the figure is a superlattice 906 on which is provided a light emitting region 907. On the light emitting region 907, there is provided an undoped region 902, followed by a second superlattice 908 and a second light emitting region 909. On the second light emitting region 909, there is provided a further undoped region 904 and a third superlattice 910, followed by a third light emitting region 911. The undoped regions 902, 904 are understood to provide a recovery layer, whereby V-pits generated at the level of the respective superlattice layers 906, 908, 910 are filled and a smooth surface is obtained. The first light emitting region 907 is configured to radiate a dominant peak wavelength that is different to the dominant peak wavelength that the second light emitting region 909 is configured to radiate, which in turn is different to the dominant peak wavelength that the third light emitting region 911 is configured to radiate. The first light emitting region 907 is configured to radiate blue light, the second light emitting region 909 is configured to radiate green light, and the third light emitting region 911 is configured to radiate red light. This structure 900, which has a thickness 912 typically between 600nm and 800nm, forms the basis for processing (which can include other growth steps) to provide a monolithic high resolution RGB micro LED array. Although the epitaxial structure 900 is shown to include superlattice layers 908, 910 and recovery layers 902, 904, in other examples, instead, one or more of the superlattice layers 908, 910, and one or more of the recovery layers 902, 904, can be made thinner by omission. Advantageously, in such cases, the blue, green and red radiating layers are separated by thinner quantum barriers of the order of 5nm to 20nm, and the thickness of the whole structure 900 can be only 100nm to 200nm.

[0112] Advantageously, structure 900 is formed in a single growth process. Advantageously, structure 900 is formed such that the light-emitting regions 907, 909, 911 are relatively closely spaced in the vertical direction (as shown by thickness 912, which includes the light-emitting regions 907, 909, 911, as well as the superlattice structure and the undoped recovery layer), and thus, subsequent shallow etching can be used to etch through the light-emitting regions 907, 909, 911 and remove some of the light-emitting regions 907, 909, 911 that are considered redundant. This has proven particularly advantageous in the following process for providing a high-resolution monolithic color array of microLEDs. Although each of the light-emitting regions 907, 909, 911 includes a single quantum well (MQW), in a further example, the light-emitting regions additionally or alternatively include a single quantum well in each light-emitting region. In a further example, the light-emitting regions additionally or alternatively include a quantum barrier layer between the single quantum wells in each light-emitting region. Advantageously, the use of thin layers with small spacing facilitates shallow etching of different regions of structure 900, for example, by using appropriate techniques such as atomic layer etching, to provide different emitting surfaces for radiating light of different wavelengths. Advantageously, shallow etching reduces the height difference between pixels and creates a softer topology, thereby facilitating further processing of the structure.

[0113] like Figure 9 The epitaxial structure 900 shown is processed in a manner similar to the epitaxial structure 100 in Figure 1 to provide Figure 10A The processed structure is 1000. Figure 10A A mask layer 1004 is shown, which is deposited on the epitaxial structure 900 and patterned using photolithography to expose the underlying epitaxial structure 900, allowing selective etching through the epitaxial structure 900, particularly through the three light-emitting regions 907, 909, and 911. This selective etching through the epitaxial structure 900 (typically using dry etching techniques) provides vias 1001, which can be filled by forming n-type overgrowth regions 1002 within them. The vias 1001 and the n-type overgrowths 1402 within them extend through the light-emitting regions 907, 909, and 911 to define the boundaries of the individual pixels. This... Figure 14 Plan view 1000' of B illustrates this, showing that pixel 1006 (only one is marked) is surrounded by an n-type overgrowth 1002 formed in the trench via 1001, effectively providing a common electrode for pixel 1006. (See diagram 1000' for details.) Figure 10A and 10BAs shown, the pixels defined by the via 1001 through the light emitting regions 907, 909, 911 each have three different light emitting regions 907, 909, 911. Thus, to provide an RGB array, the pixels are selectively etched so as to remove the undesired wavelengths in particular pixels. This is explained with reference to Figure 11A and 11B

[0114] Figure 11A It is shown how the unwanted longest wavelength is removed locally so as to leave the required light emitting region for each pixel. In the processed epitaxial structure 1100, Figure 11A it is shown that an n-type overgrowth 1002 is formed that forms a common grid cathode through all the light emitting regions 907, 909, 911. In a first pixel 1102, the second green light emitting region 909 and the third red light emitting region 911 have been etched away so as to leave the first blue light emitting region 907. In a second pixel 1104, the third red light emitting region 909 has been etched away to leave the first blue light emitting region 907 and the second green light emitting region 909. In a third pixel 1106, none of the light emitting regions 907, 909, 911 have been removed and thus are all retained. Each of the pixels 1102, 1104, 1106 is defined by the etching of the epitaxial structure 900, in particular the via 1001 through the light emitting regions 907, 909, 911.

[0115] Figure 11B It is shown how the selective etching of the light emitting regions 907, 909, 911 results in pixels that are dedicated to radiate different wavelengths. For example, the first pixel 1102 can be contacted so as to radiate blue light. The second pixel 1104 can be contacted so as to radiate green light. The third pixel 1106 can be contacted so as to radiate red light. A high resolution monolithic red green blue light emitting micro LED array can be formed by selectively dedicating the pixels to a particular dominant peak wavelength radiation. As mentioned above, although the light emitting regions 907, 909, 911 each comprise a MQW, in further examples the light emitting regions additionally or alternatively comprise a single quantum well in each light emitting region. In further examples, the light emitting regions additionally or alternatively comprise a quantum barrier between the single quantum wells in each light emitting region. Advantageously, the use of thin layers with small separation facilitates the shallow etching of the different regions of the structure 900 to provide different light emitting surfaces for the radiation of different wavelengths of light. Advantageously, the shallow etching results in a reduction in the height difference between the pixels 1102, 1104, 1106 and a softer topology, which facilitates further processing of the structure at least in relation to Figure 12A and 12B

[0116] Figure 12A ​​A thin, conformal mask layer 1204 is shown, which is patterned and opened to expose a central aperture in each pixel 1102, 1104, 1106. Once the central aperture is exposed in each pixel 1102, 1104, and 1106 (using photolithography), the epitaxial structure 900 can be selectively etched to provide vias 1201 in which p-type overgrowths 1202 are formed. Since the local longest wavelength emission region has been removed, selective etching can penetrate to the desired wavelength emission region for each pixel. Advantageously, the creation and processing of the structure are arranged together to minimize the number of processing steps to form the final structure. This is achieved in... Figure 12B It was shown in the middle, Figure 12B A planar view 1200' of the array is shown, wherein a p-type overgrowth 1202 forms a central via in each pixel 1102, 1104, 1106.

[0117] In a manner similar to that described above for monochrome single-cell high-resolution micro-LED arrays, the processed light-emitting structure 1200 can be flipped and further processed for connection to a backplate used to control the individual pixels. Figure 13A A cross-sectional view of a light-emitting array 1300 with three pixels of different colors is shown. The figure shows a first pixel 1102 configured to radiate light with a blue main peak wavelength, a second pixel 1104 configured to radiate light with a green main peak wavelength, and a third pixel 1106 configured to radiate light with a red main peak wavelength.

[0118] like Figure 13B As shown, carrier injection into each pixel 1102, 1104, 1106 is performed laterally. Although a high-resolution RGB microLED array is described with reference to a common cathode formed by an n-type overgrowth in a via defining the pixel boundary and a p-type overgrowth forming a central via in each individual pixel for backplane connections, those skilled in the art will understand that alternative embodiments, such as those described with reference to a high-resolution monochrome microLED array, can be applied to a high-resolution RGB microLED array. Furthermore, those skilled in the art will understand that, although relative to… Figure 9 The example shown in Figure 13 illustrates the formation of a via 1001 that defines the pixel boundary through the light-emitting regions 907, 909, and 911, wherein the via 1001 has an n-type overgrowth 1002, and a central via 1201 in each pixel, in which a p-type overgrowth 1202 is formed. In other examples, different implementations may be used (e.g., using a p-type overgrowth 1202 in the via 1001 to define the light-emitting surface of the pixel, while using an n-type overgrowth 1002 in the central via 1201, or using the method described in Figures 1 to 13). Figure 8Any of the implementations described.

[0119] Although the above describes pixels having a light emitting surface defined by pixels, where the pixel boundaries are defined by vias through one or more light emitting regions, such that the pixel is configured to emit light having a dominant peak wavelength, in one example, for a multi-colour structure, a common via is formed through multiple light emitting regions, and as described above, overgrowth is used to selectively etch a portion of the light emitting surface defined by the via forming the boundary to form a contact, such that the pixel can emit multiple different dominant peak wavelengths. As demonstrated in Figure 14 Fig. 13, which demonstrates a plan view 1400 of three groups of micro-LEDs defined by overgrowth 1002 formed in vias, as described above with reference to Figure 9 Fig. 13. A cross-sectional view 1400' of the structure shown in plan view 1400 is shown following the diagonal dashed line. A cross-sectional view 1400" of the structure shown in plan view 1400 is shown following the horizontal dashed line. The features shown in plan view 1400, and the features in cross-sectional views 1400', 1400' illustrate how such a structure can be achieved. Advantageously, such a structure enables tighter integration of micro-LEDs.

[0120] Advantageously, by using the above described structures and methods, a monolithic array of high resolution micro-LEDs can be provided. Such an array can comprise a single colour or a colour array, and thus can be applied to a variety of applications requiring a high resolution light emitting structure. Advantageously, the pitch of the pixels of such a monolithic high resolution micro-LED array is less than 10 microns. In some examples, the pitch of the pixels of such a monolithic high resolution micro-LED array is less than 4 microns. In other examples, the pitch of the pixels of such a monolithic high resolution micro-LED array is less than 3 microns. Although the array is described in relation to square pixels in a grid formation, other forms and patterns of pixels in the array are implemented in further examples.

[0121] The ability to form a high quality array of emitters is at least in part due to the use of a planar epitaxial structure which is formed (grown or provided) and processed with minimal overgrowth, which in turn isolates the pixels in the tightly integrated array. Advantageously, the vias through the light emitting regions of the epitaxial structure provide a means for improved electrical contact to all of the pixels in the array, which can be independently driven. Advantageously, the provision of a stack of light emitting regions means that a desired light emitting region can be identified and its surface exposed for efficient processing and contact, to provide an improved light emitting diode structure and monolithic high resolution micro-LED array.

[0122] Although the examples describe the above LED structures by growth through MOCVD, in some examples, growth through different and / or supplemental techniques is beneficial. For example, growth through MBE can enable cooler and / or slower growth rates, which can be beneficial for the above growth and processing steps. Although the above processing steps are described in any order, one of skill in the art understands that in further examples, the processing steps are performed in any order suitable to obtain the target structure.

Claims

1. A light-emitting diode structure, comprising: p-type region; n-type region; and A light-emitting region for recombination of charge carriers that can be injected by the p-type region and the n-type region, wherein at least one of the n-type region and the p-type region is at least partially formed in a via through the light-emitting region, wherein the via defines the boundary of the light-emitting surface of at least one pixel.

2. The light-emitting diode structure according to claim 1, wherein, The luminescent region includes at least one epitaxial quantum well layer, and / or wherein the via enables the injection of lateral charge carriers in the luminescent region.

3. The light-emitting diode structure according to claim 1 or 2, wherein, Both the n-type region and the p-type region are at least partially formed in a plurality of vias passing through the light-emitting region, and / or the light-emitting diode structure further includes another via, wherein the via and the other via are respectively arranged to provide an anode and a cathode.

4. The light-emitting diode structure according to claim 1 or 2, further comprising another light-emitting region, the light-emitting region and the other light-emitting region being separated by an undoped region to provide a stack of light-emitting regions, the via passing through both the light-emitting region and the other light-emitting region, wherein the light-emitting region and the other light-emitting region are configured to radiate light of different wavelengths, wherein the light-emitting region and the other light-emitting region are arranged such that the surface regions of the light-emitting region and the other light-emitting region partially overlap, wherein the light-emitting diode structure comprises at least three light-emitting regions, one light-emitting region emitting blue light, one light-emitting region emitting green light, and one light-emitting region emitting red light.

5. The light-emitting diode structure according to claim 1 or 2, wherein, The via is a mesh via that defines an array of multiple pixels.

6. The light-emitting diode structure according to claim 3, wherein, The other through-hole includes a columnar through-hole, and at least one of the n-type and p-type regions is formed in the other through-hole.

7. The light-emitting diode structure according to claim 1 or 2, wherein, The light-emitting region and / or another light-emitting region are formed on an undoped epitaxial layer, and / or the light-emitting region and / or the other light-emitting region are formed between undoped epitaxial layers.

8. The light-emitting diode structure according to claim 1 or 2, wherein, At least one of the n-type region and the p-type region is formed in a through hole that is respectively connected to the planar n-type region or the planar p-type region.

9. The light-emitting diode structure according to claim 1 or 2, wherein, The n-type region and / or the p-type region are respectively formed in the through hole by growing selected regions of n-type material and / or p-type material.

10. The light-emitting diode structure according to claim 1 or 2, wherein, The through-hole is an etched through-hole.

11. The light-emitting diode structure according to claim 1 or 2, wherein, The luminescent surface has an area based on the diffusion length of charge carriers within the luminescent region.

12. The light-emitting diode structure according to claim 1 or 2, wherein, The at least one pixel is defined entirely by the periphery of a single electrode.

13. A high-resolution micro-LED array comprising a light-emitting diode structure according to any one of claims 1 to 12.

14. The high-resolution micro-LED array according to claim 13, wherein, The array is a multi-color array, and / or the pixel pitch of the array is less than 10 micrometers.

15. A method for forming a light-emitting diode structure, comprising: p-type region; n-type region; and A light-emitting region for recombination of charge carriers that can be injected by the p-type region and the n-type region, wherein at least one of the n-type region and the p-type region is at least partially formed in a via through the light-emitting region, wherein the via defines the boundary of the light-emitting surface of at least one pixel.

16. The method according to claim 15, wherein, The luminescent region includes at least one epitaxial quantum well layer, and / or wherein the via enables the injection of lateral charge carriers in the luminescent region.

17. The method according to any one of claims 15 or 16, comprising: The n-type region and the p-type region are formed in the through-hole passing through the light-emitting region.

18. The method according to claim 17, wherein, It includes another light-emitting area, and the light-emitting area and the other light-emitting area are arranged such that the surface areas of the light-emitting area and the other light-emitting area partially overlap.

19. The method of claim 17, comprising at least three light-emitting regions, wherein one light-emitting region emits blue light, one light-emitting region emits green light, and one light-emitting region emits red light.

20. The method according to claim 15 or 16, wherein, The via is a grid via that defines multiple pixels.

21. The method according to claim 15 or 16, comprising growing the n-type region and / or the p-type region respectively in the through hole by growing selected regions of n-type material and / or p-type material.

22. The method of claim 15 or 16, comprising etching through the light-emitting region to form the via.

23. A method for forming a high-resolution LED array, comprising any one of claims 15 to 22.

24. The method according to claim 23, wherein, The array is a multi-color array, wherein the pixel pitch of the array is less than 10 micrometers.

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